DIAGNOSIS The pump is clogged with scale or the internal check valve is stuck. Minerals from hard water jam the mechanism.
FIX Run a full, strong descaling cycle. Use a commercial descaling solution or a 50/50 mix of white vinegar and water. Fill the reservoir. Run the brew cycle without coffee or a filter. Let the solution sit in the system for 30 minutes, then run 2-3 full reservoirs of clean water through to rinse.
IF THAT DIDN'T WORK The pump motor itself may have failed. The pump is part # DCB-200. Access requires disassembling the brewer. You must drain all water first. The pump is located near the water tank outlet tube.
HEADS UP Do not use citric acid-based descalers. They can damage internal rubber seals. Use vinegar or a branded appliance descaler. Perform this cleaning every 3 months if you have hard water.